Explain p-value with an example
Last updated: November 29, 2025
Quick Overview
Explain p-value in simple terms and provide a concrete example.
Citadel
Statistics & Math
Data Scientist
Citadel
November 29, 2025Data Scientist
Technical Screen
Statistics & Math
Medium
2
10
2,073 solved
Explain p-value in simple terms and provide a concrete example.
This statistics question from Citadel's Technical Screen tests your ability to apply mathematical reasoning to practical problems. The interviewer expects precise definitions, correct methodology, and awareness of assumptions and limitations.
What the Interviewer Expects
- Set up the problem formally with proper notation
- Apply the correct statistical test with clear justification
- Interpret results with appropriate caveats and confidence levels
- Discuss practical significance vs statistical significance
- Identify potential confounders and how to address them
Key Topics to Cover
Probability distributions
Bayesian vs frequentist inference
Regression analysis
Confidence intervals and significance levels
Conditional probability and Bayes theorem
How to Approach This
- Define your hypotheses (H0 and H1) clearly before performing any test.
- Calculate required sample size BEFORE running an experiment, using power analysis.
- Remember the Central Limit Theorem: sample means become approximately normal with large n.
- Watch for Simpson's paradox. Always segment data by key dimensions.
- Distinguish between statistical significance and practical significance.
Possible Follow-up Questions
- How would you handle multiple comparisons?
- What if the sample size is very small?
- How would you design a follow-up experiment based on these results?
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